This invention relates to the inspection of paneled containers to determine whether or not the containers have bulged or sunken panels. More particularly, this invention relates to the inspection of paneled containers which are made of glass.
During the production of paneled glass containers, manufacturing inconsistencies sometimes result in containersbeing produced with bulged or sunken side panels. The defective side panels cause the container volume to be incorrect, and also make labeling of the container difficult. It is therefore helpful to provide some means for inspecting the panels on the containers in order to determine if they are defective. One such system is disclosed in U.S. Pat. No. 3,343,673, issued to C. H. Thacker et al. Described is a system for gauging flasks in which a pair of reference feelers contact the wall of a container above and below the portion of the container wall which would be bulged or sunken. A pair of gauging feelers contact the portion of the container wall which would be bulged or sunken if the container were defective. The reference feelers are utilized to define the desired paths of the gauging feelers. If the gauging feelers deviate from their desired paths, the container is considered defective and is automatically rejected.
In addition to the problem of bulged and sunken sidewalls, some containers are produced which have an incorrect width measurement. Systems for gauging this type of defect are disclosed in U.S. Pat. No. 3,344,245 issued to C. W. Kulig, and British Pat. No. 1,245,592, issued to E. Evers et al.
The Kulig patent describes a system in which a pair of rotatable, tangentially opposed gauging wheels, which have pockets conforming to the body shape of the containers, embrace the containers as they move along a conveyor. The containers fit into opposing pockets of the wheels as they move. Oversize containers cause the gauging wheels to be spread apart, which in turn activates a reject mechanism. The Evers patent provides a gating mechanism which allows the passage of containers whose width is less than a certain value. If a container is arrested by the gate, the gate is temporarily opened and the container passes through the gate. The defective container is rejected as it moves down the conveyor line.
Another system, shown in U.S. Pat. No. 3,249,223, describes a system which measures the diameter of containers having lug finishes by means of a differential transformer. If the diameter is either too large or too small, a reject signal is generated and the container is subsequently rejected.
The present invention provides a system which permits the detection of containers which have bulged or sunken side panels and/or incorrect width. In order to determine if a sidewall or panel exhibits a bulged or sunken condition, the distance between a reference line and three points on the container sidewall is measured from three spaced apart points along the reference line. These measurements are utilized to determine the extent of deviation of one of the points on the sidewall from a line passing through the other two points on the sidewall. If the sidewall is flat, all three points will lie on a line. Deviation of one of the points from a line passing through the other two thus can be used to determine if the sidewall is bulged or sunken.
By making distance measurements on opposing sides of a container, a bulged or sunken sidewall can be detected on either side. In addition, by making the measurement at corresponding heights on opposing sides of a container, a width determination can be made. The width of a container can than be compared to predetermined limits in order to determine whether or not the container is defective.
In the preferred embodiment of the invention, LVDT's are utilized to make the distance measurements. Electronic circuits process the measurements to determine if a container has a bulged or sunken sidewall or an incorrect width. If the container is defective, it is automatically rejected as it moves along the conveyor.